| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 | 
                                                                 
                                    
                                    0.5%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply | 1 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    
| 0 | No obstacle | 666 | 
                                                                 
                                    
                                    46.5%
                                 
                                                             | 
                                                        
                    
| 1 | Minor obstacle | 382 | 
                                                                 
                                    
                                    26.7%
                                 
                                                             | 
                                                        
                    
| 2 | Moderate obstacle | 258 | 
                                                                 
                                    
                                    18%
                                 
                                                             | 
                                                        
                    
| 3 | Major obstacle | 101 | 
                                                                 
                                    
                                    7.1%
                                 
                                                             | 
                                                        
                    
| 4 | Very severe obstacle | 17 | 
                                                                 
                                    
                                    1.2%
                                 
                                                             |